Control means for draft regulators



Aug. 1, 194.5.

v M. w. CREW ET AL CONTROL MEANS FOR DRAFT REGULATORS Filed May 1, 1942INVENTOR MORRlS W. CREW S$ORGE A. SHORT ATTORN EYS 2 SheetS- -Sheet 1 v1945- M. W.-CREW ETAL CONTROL MEANS FOR DRAFT REGULATORS 2 Sheets-Sheet2 Filed May 1, 1942 Fla-7 T R R s 0M m TRH N mC R wA m N T SE A HG m mGB Patented Aug. 7,' 1945 CONTROL- MEANS FOR DRAFT REGULLATORS Morris W.Crew and GeorgeA. Short, Cleveland, -Ohi0,'assign0rs to The Hotstream'Heater'Com- I 1 ,pany, .ClevelamL'Ohio, a corporationof Ohio ApplicationMay 1, 1942, Serial 'No. 441,300 '5Claims. (01. 236-45) This inventionrelates to improvements in control means for "draft regulators,particularly where they involve means for preventing the flow of coolair through heating equipment during the period when the burner is shutdown.

"An object of the present invention is to provide improvements for usewith a draft stabilizer damper on the stack side of the furnace. Such adamper normally pivots freely in a, thimble mounted on the furnace pipeor'breeching, balancingthe draft 'by meansof a weight on the Y'dampe'r'so as to maintain a predetermined fur-- nace draft. An objectof thepresent invention is' to provide "means for reducingathe draftthrough the furnaceto a minimum during inoperative periods of the burneror during those periods when automatic control means is not call ing.for the production ofadditional heat; The present device also providesfor maintaining a short interval of normal draft after the burner is'shut down for the purpose ofcarrying off prodducts-of combustion fromthe last increments of fuelburned-during'the demand period. This isparticularly advantageous with oil burning equip-' ment where normaloperating draft is necessary for a short interval, generally between'lOto 15 seconds or more after the oil burner is shutoff.

'At the sametime our improved equipment provides for restoring thenormal draft immediately upon ademand for additional heat-from the fur-'nace so that combustion is immediately resumed under the most favorableconditions, and puffing and smoky start is eliminated. Another object ofthe present invention is to provide novel'automatic equipment forproduc-. 7 ing the abovenamed result by the use of a motor adapted'to bestalled without injury, thereby providing' equipment of va. very simpleform and adapted to be connected in electric circuits using customary orstandard voltages without the necessity for special transformers and thelike. Other objects and advantages will appear from the accompanyingdrawings and description and the" essential features will be set forthin the claims.

' In the'drawings, Fig. 1 is a vertical sectional View of the regulatoralong the line l-*[ of Fig.

C Fig. 2 is a similar view showing anotherposition. of the parts; Fig. 3is a fragmental'view'taken in a'similar position "to Figs. land 2 andshowing still another position of the parts; Fig. 4 is an enlargedfragmental View of certain of the ,parts' of Figs. '1, 2" and 3,-showing other positions thereof; Fig. 5 is a sectional view taken "alongthe'line' 5f 5 of Fig. 1; Fig. "6 is an enlarged.

fragment'al sectional view taken along the line 6.:6 of Fig. 5; whileFig. 7 isa diagrammatic view illustrating one use of our improveddevice.

In the'various views a furnace is shown at l0 having a .draft pipe .IIconnected with a stack 12. :Our invention may be used whether the fuelis solid, liquid or gaseous, but in the present instance We haveillustrated an oil burner I 3 having a blower M which is driven throughshaft In from motor I6. -A very satisfactory means for c'ontrolling'thedraft'for such a'furnace regardless of thetype (if-burner or fuel usedin a draft stabilizing damper I1 pivotally mounted by means of a pivot18 which-works inside pockets 18a of the damper frame. Adjustableweights l9 and 2'6 balance the damper so that the draft act- "ing in thedirection ofthe arrow of Fig. '1 and tending toopen the damper isbalanced against the weights l9 and 20 so that the desired draftconditions are maintained in the furnace regardless of changingcircumstances. Our improved device isarranged to permit this customaryaction to take place during such periods as the burner l 3 is operatingin response to a demand for additionalheat while at the same timeproviding positive meansfor'opening the damper I! to a position ofminimum draft and holding it open during stand-by periods when there isno demand'for additional heatfrom furnace H1. This prevents the "drawingof cold air through the furnace in the case of gas and liquid-firedfurnaces and conserves the heat in the furnace setting during suchstand-by periods. In the case of coil-fired furnaces it prevents theburning of'the fuel bed faster than necessary during such stand-byperiods.

Mounted at some convenient point near the damper l isa housing 2| inwhich is mounted a motor 22' of a type adapted while energized to bestalled Without injury thereto. A satisfactory Mfg. 00., Inc., andmarketed under the name Synchron, but motors satisfactory for thepurpose arefproduced by others. The shaft directly driven bythe motor isindicated at 23 in Fig. 6 and acts through aset of reduction gears 24 todrive the final shaft 25 at a very great reduction in speed as comparedto the shaft 23, The reduction here may be of the order 'ofapproximately 1750 .to 1 In other words, if the motor shaft 23 turns. at1750 R. P. M. then the shaft :25 will turn at about one revolutionper-minute.

Fastened to the shaft 25 so as to turn withit is the-bellicranklever 26.One endofthis-lever carries the pin 21. The position of the parts shownin Fig. 1 is what we have called the burner-operating position whichpermits damper I! to swing freely in response to draft demands. Theposition of the parts shown in Fig. 2 corresponds to what we have calledstand-by position and corresponds to the open position of damper l1 toprovide minimum draft, whenever heat is not being demanded of thefurnace I0. In the position shown in Fig. 1, the pin 2'1 underlies andengages a hook 28a on the upper end of bar.

28. This bar is mounted for vertically sliding and oscillating movementby means of a pin and slot connection. In the present instance a slot281) in the bar 28 receives a pin 29 which is threaded into the housing21. They lower end of bar 28 is connected by link 30 to the damper 11.It will be noted that the link fits loosely in the hole 280 of the barand passes through an elongated slot 31a of an arm 3| which is rigidwith damper H. A wing nut 32 is threaded on the lower end of link 38 toadjust this connection as desired.

The motor 22 when energized moves lever 26 clockwise as viewed in Figs.1 to 4 until lever 28 engages the stop pin 33. This position ismaintained as long as heat is being demanded from the furnace. Upondeenergization of the motor 22 spring 34 moves lever 26 in acounterclockthe depression of hook 2811 as shown in full lines in Fig. 4and because the upper end of bar 28 is prevented by the keeper nose 350,from the following the pin 21. Thereupon the bar 28 starts to falldownwardly as shown in dot-dash lines in Fig. 4, under the influence ofgravity. Thus very shortly after motor 22 is energized the damper "isreleased for its normal stabilizing action. I

In Fig. 7 we have shown a diagram illustrating one use of our inventionbut in no sense limiting ourselves to such a use alone. In this view themotor 22 is supplied with current from the lines L1, L2 which may be theusual 115 volt supply found in many installations. The motor 22- is of atype to operate on this voltage. In one of the supply lines isillustrated a thermostat 38 which may be a room thermostat or the likefor controlling the demand apparatus when heat is required from furnaceI8. Connected in circuit is the motor l6 if such a motor is requiredeither for driving a forced draft fan 14 or for driving a coal stoker orthe like. In the case of a gasfired furnace there might be no occasionfor wise direction from the position of Fig. 1 to that of Fig. 2,lifting pin 21 and bar 28 and pulling upon link 30 to positively opendamper l1 and hold it in the open position. It will be noted uponcomparing Figs. 1 and 2 that when spring 34 in Fig. 1 is in its mostextended position and therefore providing the greatest pull, it isworkingthrough a comparatively short effective lever arm as representedapproximately by the horizontal distance between the center line ofspring 34 and shaft 25. As the spring approaches the position of Fig. 2and loses some of its tension, this effective lever arm increases sothat theresult is the application of a substantially constant torque onlever 26 by the spring 34.

It will be noted that as pin 21 moves from the position of Fig. 1 tothat of Fig. 2 it travels in the arc of a circle and because of itsengagement with the hook 28a, the upper end of bar 28 must follow thesame arc, the bar meanwhile pivoting about the point 29. Means isprovided to prevent the hook 28a on the upper end of bar 28 fromfollowing this arcuate path when pin 21 moves in a clockwise directionaway from the position of Fig. 2 so as to cause pin 21 to very quicklyclear the hook 28a, thus uncoupling the releasable coupling formed bypin 21 and hook 28a and permitting the bar 28 to drop promptly,restoring damper IT to its normal stabilizing action. To this end weprovide a latch or keeper 35 pivotally mounted in the housing at thepoint 36 and overbalanced for freely pivoting action in a clockwisedirection until such movement is limited by engagement with the stop 31.A nose 35a, is formed on the keeper so as to engagein frontof the upperend of bar 28 as shown in Fig. 2 when the parts are in the stand-byposition.

The position of the parts as they are about to I reach stand-by positionis shown in Fig. 3; Here the upper end of bar 28 has engaged and liftedthe nose 35a of the keeper and on further slight counterclockwisemovement of lever 26 the parts will drop into the position of Fig. 2, atwhich time pin 29 engages the bottom of slot 281). As the parts move outof this position upon ener gization of motor 22, the releasable couplingis uncoupled, since the pin 21 soon moves out of such a motor but ourdevice would work as illusstrated in Fig. '1' without any motor 16. Inthe case of a gas-fired furnacean electrical device for turning on thegas might be supplied in place of the motor 15.

Theoperation of our device in a typical installation. would be asfollows. When thermostat 38 closed thecircuit of Fig. '7 in response toa demand for heat or more heat, the circuit would be completed throughLi, lines 39 and 48, motor 22, and line 4| to L2. Motor 22 would startat the same time that the burner l3 started to operate. Almostimmediately the parts would move as described in connection with Fig. 4so as to uncouple the releasable coupling 21, 28a and release bar 28which would drop immediately by gravity, causing'link 38 to releasedamper I! for its normal stabilizing action during the period when theburner was operating. When the parts reach the position of Fig.1, themotor is stalled by the engagement of lever 26 against pin 33. When thedemand for heat is reduced and thermostat 38 is thereby satisfied itbreaks the circuit to motor .22, whereupon spring 34 starts to move theparts from the position of Fig. l to that of Fig. 2, it being realizedthat bar 28 is held on pin 29 so that pin 21 automatically engagesbeneath and is recoupled to the hook 28a in the burneroperating positionof the parts. The swinging of lever 26 in a counterclockwise directionfrom the position of Fig. 1 to that of Fig. 2 is retarded because of thereduction gearing 24. It is impossible for spring 34 to. back-wind thereduction gearing 24 very rapidly, so that the-reduction gearingserves'with the spring 34 as a time delay means, affording a briefperiod of the order of a quarter to one-half a minute required for theparts to move from the position of Fig. 1 to that of Fig. 2. Thisprovides a short period of normal draft after burner I3 is shut downwhich is quite essential in the 'case of an oil-fired burner to preventgassing back. When motor 22 is again energized, bar 28 is released fromthe positioIT of Fig. 2 and drops immediately to the full extent of slot282), thus releasing damper ll for the immediate provision of full draftrequired for furnace operation.

Our device is thus complete in one small unit, as exemplified in housing21, which-need only be mounted near the furnace and connected to anystandard draft stabilizing damper such as V 2,381,437 1 that indicatedat n and the wires of a, 115 volt system properly connected to motor 22.We have thus provided avery simple and efficient device adapted tooperate over long periods without attention and adapted to provideexcellent furnace operating draft conditions for furnaces using manydifferent types of'fuel.

Referring again to Fig. 7, ashunt line 42 may be provided around .thethermostat. Switch 43 in this line would be normally open but might beclosed by hand if normal draft were desired in the furnace, as forfiring periods in a coal burning furnace. The parts would then move tothe Imposition of Fig. 1, regardless of thermostat38, .and normal draftwould be established. Upon reopening switch43, automatic control wouldbe resumed.

What'we claim is: v 1. Control means for a furnace draft stabilizjingdamper, comprising an electric motor adapt? ed while energized to bestalled without injury thereto, means operatively connecting said motorand said damper and having a stand-by. position for positively holdingsaid damper in a minimum draft position and also having a releaseposition for release of said damper for normal, draftstabilizing action;said connecting means comprising a lever operated by said motor and abar connected with said damper and interengaging parts on said bar andlever automatically engaged when said parts are in release position andautomatically disengaged when said lever leaves stand-by position, meansfor so disengaging them, spring means connected with said lever formoving the same to stand-by position, means for stalling said motor.when said lever reaches release position, and means energizing saidmotor only when the furnace demands additional heat. I

2. Control means fora furnace draft stabilizing dampencomprising anelectric motor adapted while energized to be stalled without injurythereto, means operatively connecting said motor and said damper andhaving a stand-by position for positively holding said damper in aminimum draft position and also having a release position for release ofsaid damper for normal draft stabilizing action, said connecting meanscomprising'a lever operated by said motor to release position andabarconnected with said damper, saidlever having a projection, saidbarhaving apin- 'and-slotmounting beneath said projection, said .barhaving at its upper end ahook overlying said lever. projection when theparts are in release position, spring means for moving said lever tostand-by'position whereby said lever projection is moved upwardly andlifts said hook and bar;

keeper means engaging said bar in stand-by position, and said leverprojection when leaving stand-by position moving in an are adapted toreleasesaid hook whereby, after, release, said hook and bar may fallfreely.

' 3. Control means for a furnace draft stabilizer damper, comprising anelectric motor adapted while energized to be stalled without injurythereto, means operatively connecting said motor and said damper andhaving a stand-by position for positively holding said damper in aminimum draft position and also having a release position for release ofsaid dampeiafor normal draft stabilizing action, said connecting meanscomprising a lever oscillatable by said motor from a stand-by positionto release position, said con- 1 necting means' including reductiongearing,

spring means for moving said lever from release position to a stand-byposition, which movement is retarded by' said gearing, said connectingmeans comprising disconnectible parts between said lever and damper,means causing disconnection of said parts by the first portion of saidlever movement from stand-by position, whereupon gravity releases saiddamper for draft sta- 1 bilizing action, said disconnectible parts beingagain connected upon reaching release position,

and means energizing said motor only when said furnace demandsadditional heat.

l. Control means for a furnace draft stabilizing damper having operatingand standby positions, comprising an operating element movable back andforth between two positions, motor meansfor moving it to one of itspositions, power means for moving it to the other of its positions,operating connections between said element *means when effectiveenergizing said power means and recoupling said coupling.

5. Control means for a furnace draft stabilizing damper, comprising anelectric motor adapted while energized to be stalled without injurythereto, means operatively connecting said motorand damper and having astand-by position for positively holding the said damper in minimumdraft position and also having a release position for release of saiddamper for normal draft stabilizing action, said connecting, meansincluding reduction gearing,.means o-peratively connected with saidconnecting means for moving the same to stand-by position against theinertia of said gearing, said connecting means also includingdisconnectible parts, means operative to disconnect said parts when saidmotor starts to move said parts from stand-by position toward releaseposition, whereby said damper is then quickly released for normal. draftstabilizing action, said parts being so constructed and arranged as tobe again operatively connected when in said release position, means forstalling said motor when said connecting means reaches release position,and means energizing said motor only when the furnace demands additionalheat.

' MORRIS W. CREW.

GEORGE A. SHORT.

